pollution

Combined Sewer Overflows are in the news again. Combined sewer overflows (CSOs) are a necessary part of the existing sewerage system, preventing sewage from flooding homes and businesses.Here in Tamerton Foliot we have a number of them that pollute our streams and Tamerton Creek. CSOs themselves are simple underground stuctures with just a manhole to identify them. Most exist on the sewerage pipe system. We have some huge sewerage pipes around us that carry all the sewage from North Plymouth to the Ernesettle works. On their way down they have CSOs, and the hours they release raw sewage is listed annually by the Environment Agency. The outlets are of course visible where they discharge into streams etc. It is licensed for SW Water to do this and working closely with the Environment Agency, Event Duration Monitors (EDMs) are being installed across the network to provide a robust and consistent way of monitoring releases. CSOs can sometimes discharge through misuse of the system. Wet wipes make up more than 90 per cent of the material causing sewers to block. 

Here are five in the area
1. Southway Drive CSO – situated in the woods north of Southway Drive at What3Words = ///lowest.adjust.mining This is a large pipe about 40cms diameter. If trying to see it just get to the area and follow your nose!

2. Whitleigh Woods CSO is another huge 40cm pipe that last year discharged for several days. Its at What3Words = ///precautions.master.tubes This is on the stream about 80m downstream of the footbridge by Borrowdale Close.

3. Further downstream, sewerage wise, all the sewage from Tamerton Foliot is pumped up hill to the big pipe that runs behind Riverside Walk. Several times last year the pumping station overflowed. The discharge pipe for Tamerton Foliot Pumping Station CSO is at What3Words = ///unrealistic.jukebox.steps This is about 50m upstream from where the stream widens out into the creek.

4. As the big sewer progresses, it runs under the middle of the Holly Park area – here another large pipe carrying sewage from the lower part of Whitleigh joins it. At the bottom of Holly Park a pumping station picks up sewage from the lower houses. This pumping station has an overflow discharging direct into the Creek is Tamerton Close CSO at What3words = ///tops.glare.grapes. This one is just by the footpath below Tamerton Close.

5. Porsham lane is a beautiful peaceful area with a pretty stream, horses etc, but under the fields is large sewer loop, dealing with sewage from Roborough, Belliver and industrial estates. This system has a CSO Haysend Farm and last year it spilled 16 times. Its at what3words = ///native.switch.civic

The Conservation Society is concerned about this pollution and monitors the data reporting on it. We have a representative working with Plymouth River Keepers, part of the Westcountry Rivers Trust.

The Environment Agency has recently released a map showing where Combined Sewer Overflows (CSO) have released sewage into water courses. Plymouth Live published it here https://www.plymouthherald.co.uk/news/plymouth-news/every-plymouth-sewage-hotspot-near-8552351

From this, we can see that a CSO behind Cheshire Drive last year had 13 spills and released sewage into the stream for an equivalent of 6 days. Tamerton Foliot Sewage Pumping Station on Station Road is also a CSO which had 32 spills releasing sewage for 71 hours.

These are licensed releases. In addition problems continue with the manole in Church Row Lane, and in the fields towards Coombe Lane.

by Nic T Brown

A while back the Conservation Society and my neighbours in Riverside Walk asked me to investigate sewage pollution in Tamerton Foliot. Here is an update:

Combined Sewer Overflows
Pollution is now topical and I guess most have heard of Combined Sewer Overflows (CSOs) whereby Southwest Water (SWW) are licensed by the Environment Agency (EA) to release sewage into the water courses. Although not exactly desirable, these work ok normally as they come into play in times of high rainfall, so the sewage is diluted.

The stream through Tamerton Foliot that leads into Tamerton Lake and onto the Tamar collects water from quite an area – basically our side of the ridge lines formed by Tavistock Road, and Budshead Road towards Ernesettle, then from the North it’s this side of the top of the village. Any pollution incident then in Belliver, Roborough, Southway, ends up in Tamerton Foliot!

There is an infamous CSO below Belliver Estate (the pin marks the manhole, and the arrow shows the discharge point into the stream) – you can find this by walking upstream along Coombe Lane then beyond.

In August 2016, the weather was dry and a pollution incident caused by the build-up of commercial-use wet wipes created a blockage in the sewerage pipe in Widewell Woods. This led to untreated sewage being released into the Tamerton Stream

This Category 1 (major) pollution incident had a substantial impact on the stream, unfortunately killing more than 80 Brown Trout. 

This incident resulted in an Enforcement Undertaking between the Environment Agency with South West Water (SWW) to the value of £350,000.

This money enabled Westcountry Rivers Trust to conduct work to improve the urban watercourses in the Tamerton stream catchment. This has led to the creation of WRT’s Plymouth River Keepers (PRK) project. I am the community’s rep on PRK and our work is on their website.

The Environment Agency has recently released a map showing where Combined Sewer Overflows (CSO) have released sewage into water courses during 2022. Plymouth Live published it here https://www.plymouthherald.co.uk/news/plymouth-news/every-plymouth-sewage-hotspot-near-8552351

From this, we can see that a CSO behind Cheshire Drive in 2022 had 13 spills and released sewage into the stream for an equivalent of 6 days. Tamerton Foliot Sewage Pumping Station on Station Road is also a CSO which had 32 spills releasing sewage for 71 hours.

Tamerton Foliot Sewerage System
Like the water system, so to the sewage flows downhill and Tamerton Foliot ‘hosts’ a major sewer taking all the sewage from Belliver, Roborough, Southway etc. It ends up in a huge pipe encased in concrete that goes under the gardens South of Riverside Walk, across the fields and onto Ernesettle Sewage Works. Most Tamerton Foliot sewage goes to the pumping station along Station Road, then deep under the stream to join the main sewer. I have obtained a full set of maps which are on the Tamerton Foliot Conservation Society Website. An extract is here:

The current day problem – Overflowing manhole covers
From the map above, you will see a major sewer coming down Coombe Valley crossing Church Row Lane and joining up with the main sewer from Southway etc. In times of high rainfall, the manhole in Church Row Lane blows and raw sewage flows down the road into the stream carrying with it waste, paper, sanitary products etc. Another manhole regularly blows below Cann Cottages and raw sewage flows down the fields into the stream.

I have been trying to bottom this out with the EA and SWW. I once had good contacts with managers of both organizations, but they have moved on. Both organizations are now impenetrable to me! I phone up the call centre and are told they work in ‘Functional Teams’ and someone will call me back… they never do!

What we can all do please, is to report an overflow as its happening and take photos. Eventually this might trigger the EA to take action against SWW to sort things. We do benefit by a community member who lives at the top of Church Row Lane who keeps an eye on the manhole there. Please can the general community help also?

The Environment Agency are the responsible body for recording and responding to pollution incidents in England – they have a dedicated incident hotline that you can call 24 hours a day, 7 days a week 0800 80 70 60 you can also report incident via email to ics@environment-agency.gov.uk

Before my contact with SWW disappeared, he reported to me the new demand on the system is thought to caused by the new Mayflower Treatment Works. There is outfall from the works, and this comes down the hill in a pipe next to the fresh water supply to the new major pumping station along
Coombe Lane. Here, the outfall enters the sewage system – so just before Tamerton Foliot. SWW told me they were trying to balance the system to relive the situation… clearly this has failed so far. However, SWW did put in a stronger manhole in Church Row Lane. The cover does not blow now,
the sewage just fountains up the cracks … before flowing down into the stream!

If anyone reading this is with the EA or SWW and can help put me in touch with managers responsible for our area please can they help?

Plymouth River Keepers mid term report is published here https://wrt.org.uk/project/plymouth-river-keepers/